Thyroid Hormone Resistance Vs. TSH-oma

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Question

My new case is a 49yr old white male referred by cardiology for abnormal TFT in July 2006. In March he had an episode of PAT/A fib which reverted to NSR.His Sx were anxiety, palpitations and dizziness.

This is a summary of his tests:

4/06 7/06 8/06 10/06 11/06 12/06 2/07

TSH(.35-5.5) 0.961 0.92 0.87 0.76 1.11 1.07

FT4(.8-1.8) 2.99 2.3 2.2 2.4 2.6 2.5

T3 212 176 1.3 1.6/223 188

(80-200) (60-180) (.9-1.8)

FT3(210-440) 471 617 511

Ab: TPO/TG and TSI are not elevated

Thyroid Uptake and Scan – 24hr uptake 35%(increased), homogenous tracer, no focal nodules

Normal thyroid on exam, positive FHx of hypothyroidism and goiter in his sister.

FSH, LH, Testosterone, Cortisol, prolactin,24hr urine catecholamines,CMP all normal.

CT Brain (could not do MRI due to chest pin) – Normal pituitary/sinusitis

Has recuurent palpitations/ boderline elevated BP, anxiety Sx, near syncope(30 day holter normal). No relief with Ativan.Sinusitis treated without relief of sx.

4/06 was given Tapazole 10tid by PCP with severe chest pain requiring D/C med.

8/06, I tried Inderal 10 bid with severe dizziness, near syncope requiring D/c med.

Finally, I convinced him to try PTU 25bid from 10/06, with initial great improvement of Sx for a month. Then Sx reoccurred and I increased PTU to 50bid in Dec/06. He remains extremely Sx- with several visits to urgent care, cardiology and calls me every week practically.Could this be a TSH adenoma or resistance? Please let me know your thoughts and what would you advice regarding further management?

Radha Reddy

Response

Your patient has a syndrome of resistance to thyroid hormone action. Do not treat him with antithyroid drugs: goiter may worsen! Try with a selective beta blocker such as atenolol. Convince your patient that high levels of thyroid hormone are important to overcome the resistance that is due to mutation in T3 receptor beta gene. Let me know what is the response to atenolol.

Paolo Beck-Peccoz, M.D